Abstract：The reliability evaluation of the distribution system becomes more and more important due to the customer's requirement for a distribution system of a higher quality. Based on the analysis of reliability for distribution systems, a variable fuzzy method is proposed. Firstly the matrix of relative membership degree is calculated based on the index feature value, the matrix of index evaluation interval, the matrix of variable range evaluation interval and the matrix of point values. Then the comprehensive relative membership degree of samples is calculated by a model of variable fuzzy evaluation. The rank feature value is thus obtained, for the evaluation. The variable fuzzy engineering method can scientifically determine the relative membership degrees of sample's indexes at level intervals, and reasonably determine the evaluation level of each sample by varying the model and its parameters. From the evaluation of the reliability of the distribution system, a relative stable value can be obtained to be regarded as the final evaluation. The case study shows that the method gives more reliable evaluation of reliability of a distribution system than the method in literature.